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Evaluating the stability of layered slopes, a common type of terrain in nature and engineering practice, poses a fundamental challenge in the field of geotechnique. The emergence and extension of tension cracks play a crucial role in the failure process of layered slopes, but accurately predicting the location of layered slope cracking and assessing its impact on layered slopes remains a challenge using conventional analytical methods. Herein, we present a closed- form solution for evaluating the layered slope stability with tension cracks without any priori assumptions. The presented closed-form solution enables the location and depth of tension crack, the critical failure surface in different soil layers, and the corresponding normal stress distribution to be determined for all single/layered slopes. Effects of tension cracks on layered slopes are investigated, considering slope inclination, soil properties, layer thickness, and dominant failure mechanism. Note that, the results show that the dominant failure mode of layered slopes could change from toe failure (without cracks) to face/base failure (with tension cracks), which has not been previously reported. Multiple cracks are possible to develop in layered slopes. The proposed closed-form solution can be applied to improve the stability assessment and engineering design of layered slopes considering tension crack. Key words: slope stability, tension crack, layered slope, closed-form solution, failure mechanisms of slopes, Introduction Natural slopes are commonly composed of multiple layers, and the stability of layered slopes can be affected by the development of tension cracks within the soil. By shortening the [...]

This study aims to investigate the effects of antislide piles and cohesion anisotropy on seismic displacements of three-dimensional (3D) layered slopes. A discrete mechanism generated by the point-to-point technique is employed as the deterministic model, and the particle swarm optimization algorithm is used to determine the least upper-bound solutions. By combining the pseudostatic approach and Newmark's method, the yield acceleration coefficients ky and earthquake-induced displacements of two-layer slopes are further analyzed in varying positions of strong/weak layers, ratios of layer strength, reinforcement locations of piles, and anisotropy coefficients of cohesion. The results indicate that for the seismic slopes (strength ratio Sr = 1.5), displacement can be reduced by an order of magnitude after pile reinforcement; considering the anisotropy results in higher safety evaluations, typically, there is generally about a 65% reduction in the seismic displacement of Sr = 1.5 slopes when coefficient kc decreases from 1 to 0.7; the optimal pile locations in anisotropic slopes may be further away from the slope toe; the presence of a strong layer at the bottom of the slope is more conducive to slope stability than in the top, but it also makes the slope stability more sensitive to changes in layer strength ratio; the destabilizing/stabilizing effect of the weak/strong layer at the slope bottom is most pronounced at low values of its proportion; switching the strong layer from the bottom to the top, the maximum values of ky experience a 25%–40% reduction, while this percentage would be magnified when calculating its impact on displacement. Moreover, different from single-layer slopes, layer heterogeneity may also result in nonuniqueness in the optimal pile locations. [ABSTRACT FROM AUTHOR]

Offshore foundations usually experience long-term cyclic loading, where the weakly bound water at the soil-structure interface can be transformed into free water. The free water enriched at the soil–structure interface would influence the mechanical characteristics of the soil near the interface, weakening the interface strength and posing a significant threat to the safety and stability of offshore foundations. This study proposed a novel concept, i.e. the characteristic water film thickness, to quantify the enrichment degree of water film at the soil–structure interface under cyclic loading. A series of cyclic shearing tests were carried out by using self-developed cyclic loading equipment combined with a small constant temperature centrifuge. The influence of different clay and salt contents on the characteristic water film thickness was investigated and analyzed. It was found that both the kaolin and salt contents significantly impacted the characteristic water film thickness, where it was positively correlated with the kaolin content while negatively correlated with the salt content. The research outcome enriched the understanding of the weakening mechanism underlying the load and deformation transfer between soil–structure interface. [ABSTRACT FROM AUTHOR]

Particle breakage usually takes place within sand when subjected to external loading, which changes the critical state line (CSL) and stress-strain behavior of sand. To consider such effect, different expressions for the CSL with consideration of particle breakage have been proposed, which can be sorted in two categories: (i) CSL through explicit incorporation of particle breakage ratio into the e – ln p′ relation, (ii) CSL through implicitly empirical correlation, e.g., e – p′0.7 and e – exp(p′ζ) relations. However, limited studies were made on comparing the performances of these expressions. This study inspects the efficiency of three representative CSLs from categories i and ii, for SANISAND modelling of sand. It was found that all the CSLs can capture the constitutive responses of sands under axisymmetric drained and undrained loads, to some extent. However, e – p′0.7 and e – exp(p′ζ) relations are comparatively simple and share an equivalently accurate performance at low to medium high pressures, whereas e – exp(p′ζ) relation works the best among others at high pressures. To more highlight the physical role of particle breakage, the CSL in category i can be suggested. Otherwise, the CSLs in category ii are recommended in modelling practices, because of the comparatively succinct expressions and less model parameters. [ABSTRACT FROM AUTHOR]

Suction caissons are being widely employed as a reliable and economic foundation to offshore wind farm. Previous studies are inconclusive in soil microstructural evolution around soil–structure. This article describes a half-caisson subjected lateral cyclic loading with the macro photography device (MPD). The microstructural probability entropy and corresponding quantification criterion are introduced to examine the effects of grain size distribution, grain orientation on monotonic, and post-cyclic moment capacities of suction caissons. The image-based results provide evidence of significant particle rearrangement occurred adjacent to the caisson wall. The variations of the grain size entropy and the orientation entropy with cycles were obviously affected by loading amplitudes, sand gradations, and position of the caisson interface, but less dependent with the loading frequency. Experimental results reveal the dominance of the grain size entropy over the moment capacity of suction caissons under different loading characteristics and sand samples. The half-model tests together with the MPD shed light on soil–structure behaviors with the microstructural evolution at the suction caisson interface. [ABSTRACT FROM AUTHOR]

This study investigated five parameters relevant to the kinematic behaviours of drag embedment anchors (DEAs), including the fluke-shank angle, the initial depth, the line thickness, the installation angle and the loading rate. A six-degree-of-freedom magnetometer system with a magnetic sensor was applied to simultaneously record the movement and orientation of the model anchor. Five groups of drag embedment tests were performed in clay with a linearly increasing shear strength profile. The anchor trajectories, pitch angles and installation load in each group were systematically compared and sufficiently analysed. This study contributes a further understanding of the kinematic behaviours of the DEA during embedment and provides a possible optimising guide in the future design of the DEA. [ABSTRACT FROM AUTHOR]